remoteproc: Change rproc_shutdown() to return a status

The rproc_shutdown() function is currently not returning any
error code, and any failures within rproc_stop() are not passed
back to the users. Change the signature to return a success value
back to the callers.

The remoteproc sysfs and cdev interfaces are also updated to
return back this status to userspace.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220213201246.25952-2-s-anna@ti.com

Documentation/staging/remoteproc.rst

@@ -49,13 +49,14 @@ might also consider using dev_archdata for this).
 
 ::
 
-  void rproc_shutdown(struct rproc *rproc)
+  int rproc_shutdown(struct rproc *rproc)
 
 Power off a remote processor (previously booted with rproc_boot()).
 In case @rproc is still being used by an additional user(s), then
 this function will just decrement the power refcount and exit,
 without really powering off the device.
 
+Returns 0 on success, and an appropriate error value otherwise.
 Every call to rproc_boot() must (eventually) be accompanied by a call
 to rproc_shutdown(). Calling rproc_shutdown() redundantly is a bug.
 

drivers/remoteproc/remoteproc_cdev.c

@@ -42,7 +42,7 @@ static ssize_t rproc_cdev_write(struct file *filp, const char __user *buf, size_
 		    rproc->state != RPROC_ATTACHED)
 			return -EINVAL;
 
-		rproc_shutdown(rproc);
+		ret = rproc_shutdown(rproc);
 	} else if (!strncmp(cmd, "detach", len)) {
 		if (rproc->state != RPROC_ATTACHED)
 			return -EINVAL;

drivers/remoteproc/remoteproc_core.c

@@ -2061,16 +2061,18 @@ EXPORT_SYMBOL(rproc_boot);
  *   which means that the @rproc handle stays valid even after rproc_shutdown()
  *   returns, and users can still use it with a subsequent rproc_boot(), if
  *   needed.
+ *
+ * Return: 0 on success, and an appropriate error value otherwise
  */
-void rproc_shutdown(struct rproc *rproc)
+int rproc_shutdown(struct rproc *rproc)
 {
 	struct device *dev = &rproc->dev;
-	int ret;
+	int ret = 0;
 
 	ret = mutex_lock_interruptible(&rproc->lock);
 	if (ret) {
 		dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret);
-		return;
+		return ret;
 	}
 
 	/* if the remote proc is still needed, bail out */
@@ -2097,6 +2099,7 @@ void rproc_shutdown(struct rproc *rproc)
 	rproc->table_ptr = NULL;
 out:
 	mutex_unlock(&rproc->lock);
+	return ret;
 }
 EXPORT_SYMBOL(rproc_shutdown);
 

drivers/remoteproc/remoteproc_sysfs.c

@@ -206,7 +206,7 @@ static ssize_t state_store(struct device *dev,
 		    rproc->state != RPROC_ATTACHED)
 			return -EINVAL;
 
-		rproc_shutdown(rproc);
+		ret = rproc_shutdown(rproc);
 	} else if (sysfs_streq(buf, "detach")) {
 		if (rproc->state != RPROC_ATTACHED)
 			return -EINVAL;

include/linux/remoteproc.h

@@ -671,7 +671,7 @@ rproc_of_resm_mem_entry_init(struct device *dev, u32 of_resm_idx, size_t len,
 			     u32 da, const char *name, ...);
 
 int rproc_boot(struct rproc *rproc);
-void rproc_shutdown(struct rproc *rproc);
+int rproc_shutdown(struct rproc *rproc);
 int rproc_detach(struct rproc *rproc);
 int rproc_set_firmware(struct rproc *rproc, const char *fw_name);
 void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type);